In the default address space, any GEP off of null results in a trap value if you try to load it. Thus,

any load in the default address space that completes implies that the base value that it GEP'd from
was not null.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112015 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 53 insertions, 4 deletions

diff --git a/lib/Analysis/LazyValueInfo.cpp b/lib/Analysis/LazyValueInfo.cpp
index e4cd867743..31ca2de283 100644
--- a/lib/Analysis/LazyValueInfo.cpp
+++ b/lib/Analysis/LazyValueInfo.cpp
@@ -457,10 +457,11 @@ LVILatticeVal LVIQuery::getBlockValue(BasicBlock *BB) {
     // then we know that the pointer can't be NULL.
     if (Val->getType()->isPointerTy()) {
       const PointerType *PTy = cast<PointerType>(Val->getType());
-      for (Value::use_iterator UI = Val->use_begin(), UE = Val->use_end();
-           UI != UE; ++UI) {
-        LoadInst *L = dyn_cast<LoadInst>(*UI);
-        if (L && L->getParent() == BB && L->getPointerAddressSpace() == 0) {
+      for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();BI != BE;++BI){
+        LoadInst *L = dyn_cast<LoadInst>(BI);
+        if (L && L->getPointerAddressSpace() == 0 &&
+            L->getPointerOperand()->getUnderlyingObject() ==
+              Val->getUnderlyingObject()) {
           return LVILatticeVal::getNot(ConstantPointerNull::get(PTy));
         }
       }
diff --git a/test/Transforms/JumpThreading/lvi-load.ll b/test/Transforms/JumpThreading/lvi-load.ll
new file mode 100644
index 0000000000..c6af7b51d6
--- /dev/null
+++ b/test/Transforms/JumpThreading/lvi-load.ll
@@ -0,0 +1,48 @@
+; RUN: opt -S -jump-threading -enable-jump-threading-lvi < %s | FileCheck %s
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
+target triple = "x86_64-apple-darwin10.4"
+
+%"struct.llvm::PATypeHolder" = type { %"struct.llvm::Type"* }
+%"struct.llvm::PointerIntPair<llvm::Use**,2u,llvm::Use::PrevPtrTag,llvm::PointerLikeTypeTraits<llvm::Use**> >" = type { i64 }
+%"struct.llvm::Type" = type opaque
+%"struct.llvm::Use" = type { %"struct.llvm::Value"*, %"struct.llvm::Use"*, %"struct.llvm::PointerIntPair<llvm::Use**,2u,llvm::Use::PrevPtrTag,llvm::PointerLikeTypeTraits<llvm::Use**> >" }
+%"struct.llvm::Value" = type { i32 (...)**, i8, i8, i16, %"struct.llvm::PATypeHolder", %"struct.llvm::Use"*, %"struct.llvm::ValueName"* }
+%"struct.llvm::ValueName" = type opaque
+
+@_ZZN4llvm4castINS_11InstructionEPNS_5ValueEEENS_10cast_rettyIT_T0_E8ret_typeERKS6_E8__func__ = internal constant [5 x i8] c"cast\00", align 8 ; <[5 x i8]*> [#uses=1]
+@.str = private constant [31 x i8] c"include/llvm/Support/Casting.h\00", align 8 ; <[31 x i8]*> [#uses=1]
+@.str1 = private constant [59 x i8] c"isa<X>(Val) && \22cast<Ty>() argument of incompatible type!\22\00", align 8 ; <[59 x i8]*> [#uses=1]
+
+; CHECK: Z3fooPN4llvm5ValueE
+define zeroext i8 @_Z3fooPN4llvm5ValueE(%"struct.llvm::Value"* %V) ssp {
+entry:
+  %0 = getelementptr inbounds %"struct.llvm::Value"* %V, i64 0, i32 1 ; <i8*> [#uses=1]
+  %1 = load i8* %0, align 8                       ; <i8> [#uses=2]
+  %2 = icmp ugt i8 %1, 20                         ; <i1> [#uses=1]
+  br i1 %2, label %bb.i, label %bb2
+
+bb.i:                                             ; preds = %entry
+  %toBoolnot.i.i = icmp ult i8 %1, 21             ; <i1> [#uses=1]
+  br i1 %toBoolnot.i.i, label %bb6.i.i, label %_ZN4llvm8dyn_castINS_11InstructionEPNS_5ValueEEENS_10cast_rettyIT_T0_E8ret_typeERKS6_.exit
+
+bb6.i.i:                                          ; preds = %bb.i
+  tail call void @__assert_rtn(i8* getelementptr inbounds ([5 x i8]* @_ZZN4llvm4castINS_11InstructionEPNS_5ValueEEENS_10cast_rettyIT_T0_E8ret_typeERKS6_E8__func__, i64 0, i64 0), i8* getelementptr inbounds ([31 x i8]* @.str, i64 0, i64 0), i32 202, i8* getelementptr inbounds ([59 x i8]* @.str1, i64 0, i64 0)) noreturn
+  unreachable
+
+_ZN4llvm8dyn_castINS_11InstructionEPNS_5ValueEEENS_10cast_rettyIT_T0_E8ret_typeERKS6_.exit: ; preds = %bb.i
+; CHECK-NOT: null
+  %3 = icmp eq %"struct.llvm::Value"* %V, null    ; <i1> [#uses=1]
+  br i1 %3, label %bb2, label %bb
+
+bb:                                               ; preds = %_ZN4llvm8dyn_castINS_11InstructionEPNS_5ValueEEENS_10cast_rettyIT_T0_E8ret_typeERKS6_.exit
+  tail call void @_ZNK4llvm5Value4dumpEv(%"struct.llvm::Value"* %V)
+; CHECK: ret
+  ret i8 1
+
+bb2:                                              ; preds = %entry, %_ZN4llvm8dyn_castINS_11InstructionEPNS_5ValueEEENS_10cast_rettyIT_T0_E8ret_typeERKS6_.exit
+  ret i8 0
+}
+
+declare void @__assert_rtn(i8*, i8*, i32, i8*) noreturn
+
+declare void @_ZNK4llvm5Value4dumpEv(%"struct.llvm::Value"*)